Filters by code or display name, case-insensitively, across all three
sections (current, selected, and remaining currencies) — a section
disappears entirely once nothing in it matches. The matching logic
lives in shared code (matchesCurrencySearch) so Compose and SwiftUI
stay in sync; SwiftUI wires it into the native .searchable() field,
Compose gets a plain search text field with a clear button.
Co-Authored-By: Claude Sonnet 5 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01FXcrACM5sok3M1KQJ8kByy